The overall objective of this research is to determine the magnitude of vertebral cancellous bone loss in comparison with bone loss in other sites in the body in the serial assessment of metabolic bone disease. Patients with steroid-induced and post-menopausal osteoporosis, mild primary hyperparathyroidism and chronic renal failure will be studied using vertebral computed tomography (CT), peripheral densitometry, quantitative iliac histomorphometry, serum chemistry and endocrine status, and calcium tracer methods. Sensitivity of bone mass measurement techniques to early changes in skeletal status will be determined.